Real time temperature monitoring is conducted in an industrial setting for process optimization, waste minimization, and energy conservation. For example, precise and real time in-vivo temperature monitoring may be used in applications such as biomedical and cancer diagnosis and during hypothermia therapy or surgery where temperature fluctuations of even a few degrees can create problems or even be life-threatening to a patient. Despite the commercial importance of this technology, the development of molecular temperature sensors has been inadequate. Although conventional contact techniques such as liquid-in-glass thermometers, thermistors, thermocouple taps, and resistance temperature detectors (RTDs) have their place, employing light as the information carrier rather than heat has several benefits. Optical temperature sensors, which are often referred to as “optodes” or “optrodes”, may be deployed in situations where it is undesirable or impossible for a wire connection, to measure temperature at a location having excessive electromagnetic noise, to monitor temperature in a corrosive environment or an explosion and importantly, to monitoring the temperature of high-speed moving parts (turbine blades, for example).
Non-contact optical approaches are also important because they provide temperature measurements with high spatial resolution, and are useful in mapping temperature for applications that require high spatial resolution, at the cellular level for example, in microfluidic chips and microelectromechanical systems (MEMS), and for locating heat “bottlenecks” in integrated circuits, and as temperature monitors for multi-well plates used in biology and combinatorial chemistry.
Remote two-dimensional infrared thermography has been used for measuring temperature. While this technique offers some of the advantages of non-contact approaches, it is limited by the strong absorption of radiation by water vapor and glass. Importantly, few objects truly behave like blackbodies, and therefore radiation from a solid object seldom exhibits a distinctive thermal signature. By contrast, luminescent signals, which are also multidimensional, offer sensitive, selective, and rapid feedback. Luminescence is often the observable of choice of chemosensors and molecular-level devices.
In the prior art, luminescent temperature sensors measure temperature using the temperature-dependent decay times of excited states of materials, intensities, excitation and/or emission wavelength maxima. There remains a need for better luminescent thermometers.